


Daddy's Little Girl

by Dark_Crystal_Demon



Category: Undertale (Video Game)
Genre: Daddy Kink, Ecto-Penis (Undertale), F/M, Possessive Behavior, Rough Sex, Roughness, S&M, Spanking, Undertail
Language: English
Status: Completed
Published: 2016-11-13
Updated: 2016-11-13
Packaged: 2018-08-30 16:39:08
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,286
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8540614
Author URL: https://archiveofourown.org/users/Dark_Crystal_Demon/pseuds/Dark_Crystal_Demon
Summary: Gaster has a Daddy kink, and you gladly play as his little girl. But today, you feel a little bratty. You tease him all day and await your punishment after everyone else goes home...





	

**Author's Note:**

  * For [NihilismPastry](https://archiveofourown.org/users/NihilismPastry/gifts).



The rest of the lab staff goes home, but you stay to finish off some last minute data collection. At least... that's what you tell everyone.

The truth is in the way you put you hair in pigtails and skip around the room when only he is watching.

Your secret is hidden under your lab coat that you have zipped up to your neck.

Only he knows your secret; since you left your shirt in his desk and your skirt in his filing cabinet.

When he came out of his office earlier in the day, it felt like his eyes were trying to burn through your lab coat as he tried to discern what gift you had for him underneath. You just smiled cutely in his direction and skipped off. Your chest bouncing with every hop.

You've felt the hollow sockets of his eyes watching you for the rest of the day. Possessive. Wanting. The lights in his sockets dimmed as you laugh at a joke Sans made and put your hand on Sans' bony shoulder.

You wished it was Gaster's shoulder you were touching, but work had to get done before play.

Still, that didn't mean you couldn't have more fun. You bent over when you didn't have to. You hitched up your lab coat when you sat down, crossing your legs. And you walked dangerously close to him whenever you passed him in the hall so that he could smell your perfume, buttercups, his favorite scent.

You knew you pushed it too far later that afternoon. His mouth made a thin frown and eyes narrowed when you stretched right in front of him. Your back arched as your arms rose into the air. The action pulled your lab coat up to the tops of your thighs, but not enough to show him your gift. You made cute stretching noises as you did it.

" **Are you quite done?** " His hands gestured as his voice entered your head for translation.

"Oh no, Daddy," you whispered just for him. You pouted, looking up at him with big eyes. "Have I done something wrong?"

His breath hitched at the name you called him. It was still hours before work ended. Another intern walked into the room and you flashed Gaster a devilish smile before you walked away.

Now no one else was here. You stand beside a lab table, looking down at your notes, but you can't concentrate on reading them. Instead you nibble on your pencil - you know he hates that habit - and twirl a finger in your hair.

" **You've been a very naughty, little girl, today,** " Gaster growls behind you. His breath tickles the exposed skin on the back of your neck. His hands cover yours to stop you from continuing to twirl your hair, and he takes the pencil from your mouth.

You take a deep breath and enjoy the sensation of his rough, porous bones against the smooth, soft skin.

You don't speak. Instead you lace your fingers into his and bring his hands to your mouth, kissing each phalange. The magic that keeps him together tingles your lips. He is so powerful. It makes you feel small but safe in his arms.

Yet tonight... tonight, you feel mischievous and let yourself lick along the edges of the holes in the carpals of his palms.

You enjoy his gasp. "Daddy, you taste so good tonight."

Dark shadows surround your vision as he presses his body against your back. Black tendrils of his magic snake over your lab coat and squeeze around the curves of your body. His magical erection feels like it's trying to burn through your clothes as he cradles himself between your cheeks. His tip pushes against the small of your back. You stop your licking and bite your lower lip in desire. "Oooooh, Daddy."

His hands crush yours painfully and you cry out. " **Bad little girls don't get rewards.** "

You bite one of his fingers in protest. The room goes deadly silent. Now you've done it.

He slams your hands under his onto the cold metal table in front of you. The table's edge cuts into your hips as he bends you over it. Gravity forces your head into your data notebook. You can smell the pencil lead from the page under your nose.

His magic keeping you in place, he removes his hands from your own and your whimper at the lose of his touch. He spanks you, " **Don't make a noise.** "

You bite your lip as he spanks you harder. And harder. You can feel the bruise on your cheek forming, and it takes all your will power not to moan. You love it, and he loves watching you struggle.

" **Apologize to your father** ," he demands, squeezing the meat of your ass that he just tenderized.

You cry out and moan as you repent, "I'm sorry, Daddy. I've been a bad girl."

He grips your lab coat and pulls it up to your waist. He sees his present. " **Oh baby girl. What have you done?** "

You were wearing frilly pink panties with a cute pattern of bones dancing along the fabric. You shake your hips playfully and say cutely, "Did I do good, Daddy?"

He spanks you for your improper grammar. You moan, relishing the punishment and then correct yourself, "Did I do well, Daddy?"

" **Yes, baby girl** ," his voice a deep gravel as catches in his own desire. He traces the frilly outline of your panties, and you shiver under his touch. Then the tone in his voice drops to a deadly octave, " **You've been keeping this from me all day?** "

Before you can say anything, you're flying off the table and slammed against the lab wall. The breath leaves you in the impact and pain bursts across your body where the wall connects with your spanked skin.

Gravity pins you there. Arms outstretched, legs dangling above the floor, your heart races as you watch him stalk towards you. His dark magic radiating around him as if he was the center of a black hole. His lab coat is unzipped, flapping in the waves of his own swirling energy. The large bulge in his pants strains against the fabric, and sweat from his bones soak into the wool of his black turtleneck. The lights in his eyes are literally burning and highlight the cracks in his skull. He is so amazingly sexy. Your panties are wet with your own desire for him. Your skeleton. Your monster. Your daddy...

You know he can see the desire in your eyes. You've never been able to hide it from him. He could see it on your face when you interviewed for the internship job. But you didn't see him reciprocate the need until you started reciting your knowledge of gravitational quantum theory. He is brilliant, but so are you. You've been studying his work all your life since the barrier broke.

"It's almost like you raised me," you'd joked at the interview. You'll never forget the moment you said it. His hands steepled in front of him. The desk between you seemed to fall away as you felt the heat between you rise. " **Indeed**."

It didn't take long for you to start spending late nights in the lab. Your passion for the work kept him close. His observations and notes captivating your mind, while you surrendered your body to his magical desire.

But sometimes you pushed his desire too far. Your games became more rough. And soon he was teaching you new things about yourself. And you trusted him implicitly...

... Even now as you squirm against the wall. He forms a Gaster Blaster beside him. The appearance of the floating dragon skull makes you scream, "No! Daddy!"

Your breath comes in short pants and your heart feels like it's going to beat out of your chest. "I'll be a good girl, I promise."

" **I am afraid I have corrupted you too much, lil' one** ," he smirks, a thin, crooked line across his skull. The Blaster warms up and opens it's mouth getting ready to fire. " **Show me your sin**."

The dragon skull blasts a laser beam that disintegrates the lab coat around you. You gasp as the blast nips at your skin, but his precision is incredible. Not a frill was singed in the attack. Your skin flushes at its sudden exposure to the room.

Gaster stands before you. He doesn't touch you. He just gazes at you. You want to wrap yourself around him, but his gravity keeps you pinned. You whine, "Daddy..."

" **What do you need, lil' one**?" He's pinned you at eye level. You shake your hips in an answer. He snatches one of your pig tails and yanks it hard. You cry out and he smiles condescendingly, " **Use your words.** "

"I need my daddy to touch me."

" **Where do you want me to touch you?** "

You blush, looking into his eyes. "Where ever I please him."

" **That could take a long time.** " His fingers twine with strands of your hair as his eyes drift to all his favorite places on your body.

"And..."

" **And?** " He pulls your hair more with your continued request. You wince, but keep going.

"I need him to punish me while he does it. So that I can earn my reward."

" **You want to earn this?** " His other hand unzips his pants. His erect member is made entirely of dark magic, ribbed and beaded for your pleasure.

You lick your lips and nod your head. "Yes, please. I'll do anything, Daddy."

He strokes his cock and you lick your lips again. " **No. You won't get off that easy. The punishment should fit the crime.** "

He tugs your hair, forcing you to bend your head to the side. His gravity forces you against the wall harder and he presses his body against yours. Tendrils of the darkness around him caress your skin and sink into your body to surround your soul. His magic was still part of the void he came out of. It always tried to consume you, but your heart was to strong to ever lose the battle. It was all a part of the game. His penis firm against your stomach and his mouth bites your ear. " **Tell me about the science experiment you did today. Don't leave out any details.** "

He gives you a devilish grin that many might find unnerving with his scarred face, but your heart only leaped at the dark promises in his eyes. He bent his head down and bit into your neck, drawing blood.

"Ahhh," you bite your lip as he sucks on your neck, marking you. You try to fulfill his challenge, but your breathing increases with every suck.

He travels down to your clavicle and bites you harder. "Yes, oh gawh, I-I... started the - ah - day looking at the particle accel-LAH-rator."

His mouth had fallen on your breast, biting your nipple through the lace of your frilly bra. " **Tell me more,** " his deep voice mumbled with your breast in his mouth.

You recite your data as he grinds his rigid and textured cock over the fabric of your panties, rubbing against your clit. You moan and search for words to explain your analysis of the data. He continues to mark every sensitive area of your body.

Finally he pushes your panties to the side between your legs. Inserting his rough, calloused fingers between your wet lips. You finish your conclusion of the day's events and end with, "Please... Fuck me."

He pulls out his fingers abruptly, making you squirm in frustration. " **Language**."

"Daddy..." Your body aches from the marks across your body and the way he admires his handiwork. " **My girl.** "

His cock teases your clit and you moan. "Please, Daddy."

" **You want this?** " He thrust against you roughly.

"Yes!"

" **You need this?** "

"Yes, Daddy! I only need you!" You plead and he obliges with a punishing hard thrust ripping inside you.

"AHHH!" You nearly cum from the insertion. Each rib and bead carve themselves inside you. "Oh, Daddy."

" **You are so wet for me, good girl.** " Pleased, he releases your limbs from his gravity. You wrap your legs around his waist; your arms around his neck. He claims your mouth as he holds you up against the wall and starts to thrust into you.

He sucks your tongue into is mouth and bites it as you feel every contour of his penis against your walls. One bead he made larger than the others just to hit that perfect spot inside you.

You moan into his mouth, and he starts to thrust harder. You squeeze your legs around his hard pelvic bones. Your feet get caught on his lab coat. His rhythm uncontinues unhindered.

You grip his scapula through his turtle neck as your legs start to shake.

" **Cum for Daddy** ," he demands, thrusting harder. He pounds against your walls, and it pushes you over the edge. You cum and ride the waves of pleasure that follow as he lets himself lose control. His thrusts become erratic and your back starts to bruise under the onslaught.

His magic bursts inside you. Dark and consuming. You mew as it tingles inside you. Then it dissipates as he pants, leaning against you and the wall. His forehead rests on yours, and, this time, he kisses you gently. You keep your limbs wrapped around him and enjoy the cool air of the room caressing your new bite marks.

" **I might have gone too far.** "

"Mmm it feels nice. Now everyone will know I'm Daddy's little girl."

He kisses you deeply and picks you off the wall. Taking you back to his office, he growls, " **All mine.** "

**Author's Note:**

> This goes out to [NihilismPastry](http://archiveofourown.org/users/NihilismPastry) who requested daddy kink Gaster. Have fun at boot camp! I'll miss you, lil' skelesis!
> 
> Check Out My Tumblr (NSFW): [Dark_Crystal_Demon](https://www.tumblr.com/blog/darkcrystaldemon)


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